Hi,
the double click on the MailBox or the Properties button, works only if you have the access right to that Mailbox.
To review access rights for all the Mailboxes in the system, you can do it from the Setting: Mailbox Browse
The register for Order Classes is common for Sales orders and Service orders. When I set an Order Class to create an Activity - it works for Sales Order, while for Service Orders - not. Is any setting...